Toilet flange

Well, I'm a first timer to the forum. Here's my question, I am remodeling my bathroom. I have to replace the 3/4" subfloor because I have a 3/4" slope. Now, the toilet flange, since it needs to be extended higher, do i cut out the old flange? or put in a new one inside the old ID flange? Your profession help is needed bad!!!!!!!

It may be as simple as adding one or two flange extenders, available at almost any place that sells plumbing supplies, incl. the big boxes.

http://oatey.com/Plumber/Shared/ProductGroupDetail/107/Closet+Flange+Spacer.html

If the flange follows the sloping floor, then extenders would end up with the flange being cockeyed on the newly leveled floor. The best location for the flange is on TOP of the finished floor, fastened through it into the subflooring. SO, the best way to resolve this is remove the existing flange, and install a new one when the floor is finished. How much gap, if any, you need to allow around the pipe would depend on the size of the pipe and the type of flange you use. Normally, it is best to use a flange mounted to the outside of the pipe, but if it is 4", you do have a choice that will work, but not recommended at all if it is a 3" pipe.

Flange

Heres my next question, I tore out the floor and replaced the 3" elbow, but I could not get the female all the way on the pipe. There seems to be only 1/2" before it went in all the way. Will this be any problem, or should I put a little silicon on the bottom of the connector pipe? Wow, lots of questions,,,,,,,,